Safety fuse for room heaters and the like



Jan. 20, 1953 A. J. HUCK SAFETY FUSE FOR ROOM HEATERS AND THE LIKE FiledFeb. 11, 1948 [71 Z07: AZ/radJHudZ. 5m 9 Patented Jan. 20, 1953 SAFETYFUSE FOR ROOM HEATERS AND THE LIKE Alfred J. Huck, St. Louis, Mo.,assignor to Knapp- Monarch Company, St. Louis, Mo., a corporation ofDelaware Application February 11, 1948, Serial No. 7,550

2 Claims. 1

This invention relates to a safety device operable to break the circuitof the heating element in a room heater or the like when the heater isaccidentally tipped forwardly on its face to a position where damagecould result to the floor or carpet if the heater were left energized insuch position.

One object of the invention is to provide a safety device which insteadof responding to an overload current therethrough, as in the usual typeof fuse, responds to increased ambient temperature caused by an abnormalcondition such as the normally open face of the heater being directedtoward a floor surface thereby resulting in the heat reflected from theheating element causing a rise in temperature ambient to the safetydevice and eventually causing the elements thereof to be separated forbreaking the circuit.

Another object is to provide a safety fuse in the form of a mountingblock and one or more tensioned spring arms which are normally connectedin the circuit by means of solder that melts at a temperature betweennormal temperature and a dangerously high temperature attained after aperiod of time with the heater in an abnormal position.

A further object is to provide a safety fuse of comparatively simple andinexpensive construction capable of convenient connection into thecircuit of a heating element and readily located in a room heater or thelike for operation as a safety factor when such operation is required.

With these and other objects in view, my invention consists in theconstruction, arrangement and combination of the various parts of mysafety fuse whereby the objects contemplated are attained as hereinaftermore fully set forth, pointed out in my claims and illustrated in theaccompanying drawing, wherein:

Figure 1 is a front elevation of a room heater with a portion brokenaway and my safety fuse illustrated therein;

Figure 2 is a vertical sectional view on the line 2-2 of Figure 1showing by dotted lines the heater in normal position and by solid linesthe heater in a position tipped forwardly on the floor;

Figure 3 is an enlarged sectional view of the safety fuse in theposition of Figure 2 showing it in the operated position.

Figure 4 is a diagrammatic view showing the connection of the safetyfuse in the circuit of the heating element.

Figure 5 is an exploded perspective view of the parts of the safetyfuse, and

Figure 6 is a sectional view similar to Figure 3 showing a modified formof safety fuse.

On the accompanying drawing I have used the reference numeral ID toindicate in general a room heater. The heater H! is supported by feet I2and [4, the normal position being that shown in Figure 2 by dottedlines. A handle [6 is provided at the back for carrying purposes.

Within the casing of the heater a core 18 of insulating material isprovided around which a heating element 20 is wound. A heat reflector 22is positioned back of the heating element, and a shield and reflector 24is positioned in front of it. The open front of the reflector 22 iscovered by a safety grill 26.

The invention here involved is a safety fuse indicated generally at SF.It comprises an installing base 30 of porcelain or the like having anopening 32 for mounting as on an end wall M of the reflector 22 by meansof a bolt 43.

The base 30 has a pair of openings 34 through which rivets 40 extend.The surface of the base 39 is grooved to receive'and position a pair offuse links 36 formed of suitable sheet metal and made of the approximateshape shown in Figures 3 and 5. These links are provided withperforations 38 through which the rivets 46 extend for mounting the fuselinks on the base. The sides of the groove in the base 30 prevent thelinks from turning on the rivets.

The fuse links are provided with eyes 42 with which wires 48 and 50 areconnected, the wires extending to the heating element 28 and to aservice plug 44, respectively. The heating element 20 is also connectedby a wire 46 to the plug 44 as is most clearly shown in Figure 4.

The fuse links 36 are normally soldered together as indicated at 52 andas shown in both the solid line and the dotted line positions in Figure2. Referring to Figures 3 and 5 it will be obvious that the links haveto be sprung toward each other for soldering together at 52. It will beobvious that when the solder melts the links will spring apart as inFigure 3 since they are under tension as just described.

A room heater or similar appliance is used normally in the uprightposition as shown by dotted lines in Figure 2 in which position thetemperature attained at the supporting surface such as the floor surface23 is low. Accordingly there is no charring of the wood of the floor norof a carpet when one is used to cover the floor. However, if the heateris accidentally overturned so that it falls on its face as shown bysolid lines in Figure 2 the radiant heat is concentrated on thesupporting surface 28 and charring of that surface may result due to therise in temperature.

In order to prevent this latter condition it is of having two links.

common practice to use a large internal volume heater which results inpoor radiant heat focusing, or a radically outwardly bulging guard at26. The result is a large and bulky appearing appliance and it is notvery practical or desirable. Another method is to use a weight actuatedswitch, or a mercury switch rigidly mounted in such manner that themercury falls away from the electrodes when the heater is tipped faceforward. These types of switches are relatively expensive and undercertain conditions may fail to operate. Accordingly, I have provided asafety device as disclosed and the result is asafety means that isreliable in operation and inexpensive to fabricate and assemble in theheater.

When the heater tips forwardly as in Figure 2 the concentrated heatraises the temperature so that in about five minutes it may be advancedfrom only 250 F. to 550 F. By using a solder at 52 that melts atapproximately 450 F. the fuse will open in approximately 3 minutes afterthe heater is tipped forward. This opens the heating element circuit andthereby prevents excessive temperature on the supporting surface 28under such abnormal condition.

I have found that an ordinary eutectic solder such as tin or tin andlead solder is suitable for my purpose. The fuse links 36 should be ofspring brass, Monel or nickel capable of retaining their springcharacteristics regardless of the rise in temperature.

The safety fuse SF may be located as shown in a closed compartmentbeyond the reflector end wall 4i and is thus out of sight, so as not tomar the appearance of the heater. I find that it operates verysatisfactorily in this position although it may be mounted in anexposed-position within the reflector 22 if found desirable.

While I have'describedthe safety fuse in connection with a room heater,obviously it can be used in other appliances wherever applicable. It canalso be made with a-si-ngle fuse link instead Figure 6 shows such anarrangement. A single fuse link 3611 is mounted by the lower rivets 40aand is soldered at 52a to the upper rivet 40a. The initial shape of thelink 36a is shown dotted and it springs to this position for breaking.the circuit when the solder melts.

Some changes may bemade in the construction and arrangement of the partsof my device without departing from the real spirit and purpose of myinvention, and it is my intention to cover by my claims any modifiedforms of structure or use of mechanical equivalents which may bereasonably included within their scope.

I claim as my invention:

1. In a safety device for room heaters and the like, a pair of fuselinks soldered together under tension whereby they will separate uponthe solder melting, said safety device remaining soldered at normaltemperatures when the room heater operates in the normal manner andbeing located in the open face of the heater so that the temperatureattained within a few minutes after the heater tips forwardly on itsopen face due to heat reflected back from the surface on which theheater is tipped melts the solder and thereby permits separation of saidfuse links, said fuse links being connected in series with the heatingelement of said room heater.

2. In an electrical appliance having a heating element and a reflectorfor reflecting heat therefrom, safety means comprising a tensioned fuselink and a current carrying element having adjacent surfaces thereofsoldered together whereby melting of the solder permits theirseparation, said link and element being located in said reflector, beingconnected in series circuit with said heatingelement, being capable ofremaining 'soldered together at normal operating temperatures withinsaid reflector, and being located so that concentrated heat on asupporting surface when the heater is tipped to a non-normal positionwith said reflector directing the heat of said heating element to saidsurface will cause suffi- -cient rise in temperature of the heatreflected by said surface back to said safety fuse for melting saidsolder.

ALFRED J. I-IUCK.

REFERENCES CITED The following references are of record in the file ofthispatent:

UNITED STATES PATENTS

